Self-grounding clip for the mounting strap of an electric switch or receptacle

ABSTRACT

A self-grounding clip is provided for snapping into the screw slot of an electric switch- or receptacle-mounting strap and comprises a plate-like body portion having a central cut-out portion cut and bent about parallel fold lines to form two bent legs adapted to snap-fit into the screw slot, one end of the body being also bent out of the plane thereof arcuately about a fold line parallel to the fold lines of the central body legs and adapted to engage the end of the receptacle strap proximate the screw slot.

United States Patent 91 Longworth, Jr.

[ 1 Sept. 10, 1974 [22] Filed:

[ SELF-GROUNDING CLIP FOR THE MOUNTING STRAP OF AN ELECTRIC SWITCH ORRECEPTACLE [7 5] Inventor: Edward Longworth, Jr., Fair Haven,

Mass.

[73] Assignee: John I. Paulding, Inc., New

Bedford, Mass.

June 29, 1972 211 App]. No.: 267,386

[52] US. Cl 339/14 R [51] Int. Cl I-I0lr 3/06 [58] Field of Search339/14 R; 24/73 B, 73 SC,

24/73 SM, 73 SB; 16/2, 3; 51/4175; 85/80 [56] References Cited UNITEDSTATES PATENTS 3,663,919 5/1972 .laconette 339/14 R 3,713,071 1/1973Poliak et a1. 339/14 R FOREIGN PATENTS OR APPLICATIONS 1,302,866 7/1962France 24/73 SC Primary ExaminerBobby R. Gay Assistant ExaminerRobert A.Hafer Attorney, Agent, or FirmPennie & Edmonds 57 ABSTRACT Aself-grounding clip is provided for snapping into the screw slot of anelectric switchor receptaclemounting strap and comprises a plate-likebody portion having a central cut-out portion cut and bent aboutparallel fold lines to form two bent legs adapted to snap-fit into thescrew slot, one end of the body being also bent out of the plane thereofarcuately about a fold line parallel to the fold lines of the centralbody legs and adapted to engage the end'of the receptacle strapproximate the screw slot.

3 Claims, 6 Drawing Figures PAIENIEBSEH 01914 3 FIG. 2

' FIG. 1-

' FIG. 3

FIG. 5

1 SELF-GROUNDING CLIP FOR THE MOUNTING STRAP OF AN ELECTRIC SWITCH ORRECEPTACLE This invention relates to an attachment for the mountingstraps of electric switches and receptacles and, more particularly, to aself-grounding clip for such mounting straps.

Electric switches and receptacles for wall-mounting in a junction orreceptacle box are conventionally mounted on a metal strap adapted tospan the open face of the box and to be secured thereto by mountingscrews. For this purpose, the ends of each strap outboard of the mountedswitch or receptacle are provided with a screw slot or hole somewhatlarger than the diameter of the mounting screw so as to permit limitedlateral movement of the mounting strap as it is being secured in place.The oversize screw slot results in limited contact between the head ofthe mounting screw and the mounting strap itself and thus cannotgenerally meet the heat-rise test for an electrical ground connectionbetween the receptacle and the box. As a result, in order to providesuch a connection, it has been proposed to supply the mounting strapwith a grounding clip which heretofore has had to be welded, staked orriveted to the strap.

I have now devised a self-grounding clip for a switchorreceptacle-mounting strap which snaps into operative position and doesnot require welding, staking, riveting, or other independent connectionmeans, for insuring the proper grounding connection between the mountingstrap and the mounting box. The selfgrounding clip of the inventioncomprises a plate-like metallic body the central portion of which hasintegrally formed tongues cut and folded about parallel 'fold lines outof the plane of the body into shapes adapted to be inserted into a screwslot in one of the mounting straps carrying an electric switch oroutlet. One end of the plate-like body is bent arcuately out of theplane of the body about a fold line parallel to the fold lines of thecentral body tongues and is adapted to engage the end of the mountingstrap proximate the screw slot. The central body legs are preferably sospaced as to resiliently engage the screw slot and to be further spreadapart into engagement with the strap by the action of a mounting screwinserted therebetween.

These and other novel features of the self-grounding clip of theinvention will be more readily understood from the following descriptiontaken in conjunction with the accompanying drawing in which:

FIG. I is a plan view of the self-grounding clip body showing the cutlines that define the tongue portions thereof;

FIG. 2 is a sectional elevation of the clip of the invention;

FIG. 3 is a perspective view of the first step in mounting of the clipon a mounting strap;

FIG. 4 is a side elevation in section showing the clip in its mountedposition; and FIGS. 5 and 6 are side elevations, partly in section, ofthe clip in position in a mounting strap assembly with a flat head screwand a chamfered head screw, respectively.

As shown in FIG. I, the self-grounding clip of the invention comprises aplate-like body 10 of resilient, electrically conductive metal such asphosphor bronze,

red brass, beryllium copper, or the like, thecentral portion of which isprovided with an H-shapedcut line 11.

so as to define integrally formed tongues 12 and 13. These tongues arebent downwardly out of the plane of the plate-like body 10, as showninFIG. 2, about parallel fold lines 14 and 15 located at the top andbottom of the H. The portions 12a and 12b of the tongues adjacent theirfold lines are advantageously flat and are inclined at an angle of aboutto conform with the slope of the undercut side of a conventional screwhead if such a mounting screw is used. The remainder of each tongue isprovided with a continued curvature 12b and 13b in a reversingdirection. The ends and of the tongues terminate at a distance from oneanother slightly greater than the width of the screw slot 16 into whichthey are to be inserted. The end 10a of the body proximate one of thetongues is also bent out of the plane of the body in the same directionas the tongue but is provided with a curvature opposite to that of theproximate tongue 13.

The clip is secured in place as shown in FIG. 3, by first inserting theend 17a of the mounting strap 17 between the pincher-like curved end 10aof the clip and the proximate tongue 13 and by then rocking the clipabout its curved end 10a until the tongues 12 and I3 snap into the screwslot 16 in the mounting strap. By virtue of this rocking and snap-fitaction, the pincherlike curved end 10a of the clip and the cliptongues12 and I3 engage the mounting strap, as shown in FIG. 4, and will notshake loose. Thereafter, as shown in FIGS. 5 and 6, a conventionalmounting screw 18 is forced between the tongues 11 and 12, thus movingthem further apart until the ends 12c and 13c of the tongues engage thebody of the mounting strap 17. As a result, the tongues of the clip makeuniform contact with the mounting strap 17 so that, when the mountingscrew I8 is tightened to hold the mounting strap in place in aconventional mounting or junction box, there will be a thorough groundand heat-rise connection between the mounting screw, the receptacle orswitch, the mounting strap and the box.

It will be seen, accordingly, that the self-grounding clip of theinvention will remain in position on the mounting strap prior toinstallation of the strap, that the clip makes a self-groundingconnection between the mounting strap and the mounting box when themounting screw is tightened, and that this contact is achieved withoutrecourse to any welding, staking, riveting, or other separatecontact-making operation. If it is desired to maintain a slot-likeopening for adjusting the position of the mounting strap, the ends ofthe sides of the H-shaped cut lines can be interconnected by oppositelybowed cut lines 19 and 20 so as to remove side portions of the clip body10 and thus widen the transverse dimension of the clip opening for themounting screw 18.

I claim: A

I. In combination with a substantially flat mounting strap, at least oneend portion of the mounting strap defining an aperture for reception ofa mounting screw, 21 self-grounding clip comprising a plate-likemetallic body, the central portion of which has integrally formedtongues cut and folded about parallel fold lines out of the plane of thebody, said tongues being positioned within the aperture of said mountingstrap, one end of said plate-like body being bent arcuately out of theplane of said body about a fold line substantially tion ofa mountingscrew inserted therebetween.

3. The combination according to claim 1 wherein the end portion of eachtongue adjacent the plate-like body forms an angle therewithsubstantially the same as the I undercut angle of a mounting screw head.l

1. In combination with a substantially flat mounting strap, at least oneend portion of the mounting strap defining an aperture for reception ofa mounting screw, a self-grounding clip comprising a plate-like metallicbody, the central portion of which has integrally formed tongues cut andfolded about parallel fold lines out of the plane of the body, saidtongues being positioned within the aperture of said mounting strap, oneend of said plate-like body being bent arcuately out of the plane ofsaid body about a fold line substantially parallel to the fold lines ofthe central body tongues and in engagement with the end of the mountingstrap proximate the aperture thereof.
 2. The combination according toclaim 1 wherein said central body tongues are so spaced as toresiliently engage the apertUre and are capable of being spread apartfurther into engagement with the strap by the action of a mounting screwinserted therebetween.
 3. The combination according to claim 1 whereinthe end portion of each tongue adjacent the plate-like body forms anangle therewith substantially the same as the undercut angle of amounting screw head.